There is a vehicle lighting device including a socket which has a mounting portion mounted on a vehicle lamp, and a substrate which is stored on an inside of the mounting portion and on which a light emitting diode, a control element, and the like are mounted.
In such a vehicle lighting device, in order to miniaturize the vehicle lighting device and to increase a substrate area, a technique, in which a corner portion of the substrate is provided on an inside of a mounting portion and is provided in the vicinity of an outside surface of the mounting portion, is suggested. In this way, it is possible to reduce the vehicle lighting device and to increase the substrate area.
Here, in recent years, an advanced function and a multi-function of the vehicle lighting device are processed. Therefore, the number and types of elements and members provided on the substrate tend to increase. If the number and types of elements and members increase, it is necessary to increase the substrate area. In this case, if an external dimension (sectional area dimension) of the mounting portion is increased, it is possible to increase the substrate area. However, if the external dimension of the mounting portion is increased, it is difficult to mount the vehicle lighting device on an existing vehicle lamp. In addition, if the external dimension of the mounting portion is increased, miniaturization of the vehicle lighting device cannot be achieved.
Therefore, development of a technique capable of further increasing the substrate area is desired.